Moldable fiber composition



June 19, 1945 A. J. HANLEY MOLDABLE FIBER COMPOSITION INVENTOR A4552 J/m/vur BY ATTORNEY Patented June 19, .1945

'MOIDABLE ma coMrosrnoN Albert J. Hanley, Edgewood, B. I., assignor to Bakelite Corporation, New York, N. Y., a corporation of New Jersey, and to Respro Inc., Cranston, R. I., a corporation of Rhode Island Application July 9, 1940, Serial No. 344,481

7 Claims.

This invention relates to moldable fibrous compositions including resinous binders that are intended for hot-press molding into shapes requiring flow or extensibility of the compositions during molding and to the manufacture of such compositions.

For imparting strength and shock resistance to moldable compositions including resinous binders it is customary to include fibrous materials as fillers. These fall into two distinct types: (1) wood fiour or other finely divided materials, and (2') continuous water-laid fibrous sheets as paper or woven fabric as duck, canvas, etc. The wood flour compositions are characterized by flow during a molding operation and accordingly are moldable into any configuration or complex shape; but articles molded therefrom have tensile and impact strengths which are insufilcient for many uses that molded articles could otherwise satisfy. On the other hand articles made from continuous sheet compositions are generally high in strength and shock resistance; but the compositions have no give or extensibility and therefore can only be molded under simple compression into plates and tubes. Each type accordingly is seriously deficient from the point of view of combining moldability requiring substantial fiow with high strength values. r

It is known that the high strength values of continuous sheet compositions depend upon the incorporation of long oroverlapping fibers whereby the strength of the fibers is transferred to the continuous sheets, and the present invention makes use of this fact by incorporating such fibers. But, unlike paper and woven fabric compositions heretofore used, the compositions of the present invention possess extensibility, i, e.

lay fibrous slivers upon a moving carrier belt. The fiber laps-that are fed to the cards can be waste materials of any fibrous nature as cotton, etc., and any mixture thereof; this waste, for example, can be the accumulation of by-products of fiber textile operations such as is obtained from combings, or processed stock produced from shearlngs, spool ends, and various other normal wastes in woven textile mills. The fibers can be individual, as in the case of comber waste, or they can be fibrous elements as threads from spool ends or rag cuttings. In place of waste fibers there can be used coarse and cheaper base fibers such as. hemp, jute or sisal. New cotton can be used, and economies result from the elimination of spinning and of weaving into a fabric. Not only can spinnable fibers be used, but fibers ordinarily considered too short for spinning can proximately one-quarter of the fiber can be they have the fiow requisite for molding under the action of a force or plunger into widely varying shapes other than fiat plates or tubes; at the same time the products molded therefrom have .a surprisingly unexepected strength and resistance to shock approaching or even superior to compositions made from woven canvas fabric. The invention rests on the discovery that fiber textiles that are of flimsy or of dimensionally unstable character, and preferably so unstable as to necessitate support and some means for preserving the textile iormation during the incorporation of a binder, have the property of fiow necessary to a molding operation and retain this flow subsequent to the application of the binder.

The textile sheet or structure is produced by causing a series of garnets or cards to severally placed the length of .the goods, one-quarter across the goods and one-quarter each in the direction of 45 to the length and breadth of the material.

The wadding of any pre-determined weight is treated in a saturating machine hereinafter described with any of the known types of resinous varnishes or solutions ordinarily used for impregnating or coating as for example, alcoholic solutions of phenol-formaldehyde and other heatsetting resins. Textiles of dimensional stability, such as woven fabrics, can be saturated with binders by the simple act of immersing in a solution and pressing or wringing out excess of binder. In contrast to the ease with which woven structures are handled or treated, textile structures of a flimsy or dimensionally unstable character are saturated with difliculty, and the difliculty accompanying such saturation is ahnost proportionate to the extent of bonding between the elements or fibers of the textile structure. Waddings as herein described, which are built up of a series of slivers from a carding or garnet machine are extremely fiuffy and bulky, as ilv lustrated by the ordinary roll of. absorbent cotton, and they present extreme difficulty in the treatment with binders; the fibers because oi'v their independent positioning and their unbound contacts with neighboring fibers have a tendency thus be accomplished, and they can be delivered in a saturated condition in the same textile form in which they were orginally presented.

The waddings are found to be particularly receptive to resins, and the resin distribution is substantially uniform throughout the entire wadding structure. This distribution is one that is not realized in the ordinary varnish-treating of woven textile sheets which arenormally characterized by heavy resin deposits on'the surfaces but with very low if any resin concentration within the sheets; due to the twist in making the threads of fabrics, the fibers snug one another very tightly with but very little air space between them to form capillaries following the threads to the fabric surfaces and thereby promoting fiow to the surface with evaporation of solvents. In a wadding, however, there is an extremely loose open structure and the points of contact between adjacent fibers are very small and relatively far apart with substantial absence of capillaries, and whatever capillary action there may be is in the direction of the fibers that lie parallel to the surfaces of the wadding; this allows a fluid resin or solution to distribute itself readily and uniformly throughout the fibrous structure without any great accumulation of resins upon the two exterior surfaces. ture, characterized by low density and high absorption, permits introduction of fluid resins or solutions of high concentrations, and material economies are thereby effected through savings realized in the reduced solvent cost.

The resin distribution appears to be in the nature of coatings on the individual fibers or elements so that there is imparted to them the improved qualities not possessed by the wadding, of low water absorption, high dielectric strength, and other desirable electrical and mechanical properties. An improved resin to fiber relationship must yield hnproved results in the molded articles, and experience indicates that it is the uniformity of resin distribution among the fibers that produces the "marked superiority found in the molded articles.

The character of the fusible resinuous binder used in this process can vary over a wide scope; and it is necessary only that the binder become sufiiciently fluid, either by heating or by placing it in solution, so as to have at least no more than a dough-like consistency during the saturating step and also that in a molding operation it fuses or flows sufiiciently under the action of heat or pressure to permit extensibility of the wadding. It is more usual for the solutions to be quite fiuid and have a consistency somewhat similar to that of cream; but the application is not restricted in its viscosity requirements, and solutions as.

thin as water can be readily used without disruption of the wadding and yielding uniformly Moreover, the wadding struc-,

saturated sheets. Nor is the invention dependent on the type of resins used; the resins can be thermoplastic as well as thermosetting in name, though thermosetting phenol-formaldehyde resins are preferred on account of the properties contributed by them.

Thesubsequent drying operation need not depart from standard practice. It has this advantage; however, that because of its permeability air can be blown or drawn through the wadding. In order to reduce the bulk factor which is very high in a textile structure of this nature, it is I tile sheets of this invention have been found to by mine and construction workers. duced heretofore from resin-treated woven duck fiow with such easeand accuracy during molding that deep-drawn articles can be molded from fiat sheets withoutany preforming or preliminary packing into a mold.

The flow characteristics of the dried saturated sheets allow very intricate and irregular shaped objects to be moldedj and the molded products therefrom are free from unsightly breaks and Jagged pieces of fabric, being uniform and free from stress or strain marks. This property is strikingly demonstrated in the molding of headcoverings such as safety helmets or caps worn Helmets prohave shown broken and tom sections particularly in the crown where it is subject to stretch in the molding operation. Where the fabric is tom the helmet is naturally weak as the resin in such areas lacks the beneficial reinforcing of the cot- The flow characteristics of this new material on the other hand are such that the fibers are equally distributed over the entire area and there is freedom from any tears; the strength over the entire area is substantially uniform.

Inthe accompanying drawing there is illustrated diagrammatically a saturating apparatus showing the essential features, but it is to be understood that a supporting frame and accessory devices to insure calibration and control, not

shown, are included for practical operations.

Fig. 1 is a vertical side view, partly in cross section of a simple form of saturating apparatus;

Fig. 2 is a similar view showing a modified form of saturating apparatus;

Fig. 3 is a magnified cross section of a wadding showing the layers as formed by laying the slivers in different directions; and

Fig. 4 is a further magnified cross section ,to show resin distribution on individual fibers after impregnation and drying.

The saturating apparatus as shown in Fig. 1 includes a pan In for an impregnating liquid S; the pan is provided with a heating jacket II to control the fluidity of the solution or liquid resin. Within the pan there is mounted a guide roller l2 and a second cooperating rollenli'can also be provided.

The essential feature of the apparatus is a pair of coacting belts I5 and I6 between which the adjacent fibers in the position vided. It is preferable, however,

are or flexible permeable material as duck or similar woven fabric or wire mesh screening, are continuous and are guided in their travel by a series of rollers. To maintain the belts under independent and tight tension there is provided by the tension-regulating rolls i1 and I8, one for each belt at a point preceding their entry into the bath. The emerging belts pass between rolls I9 and 20 which are mounted so that they can be separated by predetermined distances; driving means 2| are connected to these rolls for'maintaining the belts in motion.

The wadding W is nipped and I8 at the entering point 22 or rolls l1 and Hi. The belts compress the wadding and maintain it in this form. For proper operation it is necessary that the belts be maintained under high tension to keep them in close relationship and press against the fibers to hold them fixed when the saturating fluid S is caused to flow vigorously through the belts by agitation or other means. Wherr the tension-is great the belts, being firmly pressed against the fibers, maintain the most delicate fibershaving practically no coherence with they were in before saturation.

The modification oi. the saturating apparatus shown in Fig. 2 provides a succession of immersions. For this purpose a single pan can be proto have a series of solut ons of different concentrations ranging from dilute to the most concentrated, and accordingly the pan 30 is made with separating partitions ii, 32, providing sections 33, 34 and 35. In each section is a guide roller I! as before and between the belts I51 In both the belts with the wadding between them pass between upper guide rolls l9 and 20; each of thesepairs of upper rolls can be made adjustableso as to act as squeeze rolls for controlling the quantity of impregnating fluid within the wadding or only the last pair need be so mounted.

In the operation of the impregnating apparatus the wadding W is nipped and compressed between the belts by the rolls l1, It. It is maintained in the compressed form by the tension on the belts as it is drawn through the saturating bath 8. As the wadding is released from the belts after passform over a mold reactive phenol-formaldehyde resin and when dried containing from 50 to 54 per cent of resin by weight; the tensile strengths averaged over 14,000 pounds per square laminations and over 13,500 pounds per square inch crosswise of the laminations while the impact strengths of notched specimens averaged lengthwise of the laminations bver 10.5 ioot-' pounds for an inch square and crosswise about foot-pounds for an inch square. The strength properties show up particularly in gears cut from the laminated stock; comparison tests with standard resin-impregnated canvas stock gave the 101-. lowing results:

Wadding Canvas stock s took Rated load H. P l. 121 v 1. 161 Average tooth thickness. 1947 1910 Average wear on teeth in inches after 24 hours:

At normal load (N. L.) .0045 0 At 2 X normal load (N. L.; At 3 X normal load (N. L. .0100 ma. 5 (4XN. L.) 8} (3XN.L.)

Gear failed after ho cases the gear stock was .375 inch thick.

The impregnated waddings can include other constituents such as pigments and Other loading substances; among such substances are molding material fines or powder obtained by grinding a blended composition of wood flour and heat-reactive resin. They can also be combined with other sheet materials and particularly rubber sheets which are elastic and therefore do not interi'ere with the moldable properties.

impr ated waddin s it is'sufllcient to merely placea wadding in flat sheet cavity and force the sheet into the cavity by the force or plunger; this is so because the wadding flows under the impress of the plunger to uniformly distribute itself in accordance with the, mold shape without tearing. Heat is simultaneously applied to fuse or soften the binder so that the wadding can distribute itself without hindrance; the wadding can be preheated In the molding of the to aid in this operation. In general moldpresing between the squeeze'rolls l9 and the resiliency of the fibers opens up the wadding to an extent dependent more or less on the adhesiveness of the impregnating fluid and other factors;

generally with a liquid phenol-'-formaldehyde resin the wadding approaches its original apparent density upon release from the belts.

While the impregnating apparatus is particularly adapted to the handling of waddings, it is also useful for the impregnation of felts, low density papers, knit goods and generally materials which deform or may be destroyed by the application of tension.

In Figs. 3 and 4 are illustrated magnified sections of the wadding W. Fig. 3 shows the fibers disposed in layers 5|, 52, obtained by positioning the slivers in different directions. In Fig. 4 there are shown individual fibers with coatings 55 of resin thereon.

sheet composition having the sures of about 2000 pounds per square inch are used and the molds are heated to about 300 F.: for the molding oi! helmets about a six minute molding period is used.

What is claimed is:

1. Article molded from a continuous sheet composition having the extensibility and flow under molding conditions of heat and pressure required for the molding of deep-drawn shapes and comprising in combinat'on a wadding of positioned overlapping fibrous elements, laid as dry nonfelted slivers of dimensionally unstable character, and a binder of a resin distributed within the wadding, said article having substantial uniformity in the distribution of the fibrous elements and freedom from stress and strain marks.

2. Head covering molded from a continuous extensibility and flow required under molding conditions of heat and pressure and comprising in combination a wadding of positioned overlapping cotton fiber elements, laid as dry non-felted slivers of dimensionally unstable character, and a binder comprising a resin of the thermosetting type distributed within the wadding, said covering having substantial uniformity in the distribution of the fiber elements and freedom from tears.

3. Moldable continuous sheet composition having the extensibility and flow under molding coninch lengthwise of the I ditions of heat and pressure required for molding deep-drawn shapes and comprising in combination a wadding oi positioned overlapping fibrous elements, laid as dry non-felted slivers of dimensionally unstable character, and a binder oi! a. resin in a fusible state distributed within the waddins with the latter in the dimensionally unstable condition.

4. Moldable continuous sheet composition having the extensibility and flow under molding conditions of heat and pressure required for molding deep-drawn shapes and comprising in combinatioh a wedding of positioned overlapping fibrous el ments, laid as dry non-felted slivers of dimensi nally unstable character, and a binder of a resin in a fusible state distributed within the wadding by impregnation with the binder in so lution of the wadding with the latter in the absorptive, dimensionally unstable condition.

5. Moldable continuous sheet composition having the extensibility and flow under molding conditions of heat and pressure required for molding deep-drawn shapes and comprising in combination a wadding 01 positioned overlapping fibrous elements, laid as dry non-felted slivers of dimensionally unstable character, and a binder of a resin in a fusible state distributed within the wadding by impregnation with the binder in solution of the wadding with the latter in the ab= sorptive, dimensionally unstable condition, said composition being in a dry and compressed form.

6. Composition according to claim 3 in which the fibrous elements are cotton.

7. Composition according to claim 3 in which the resin is a thermosetting resin in a fusible state.

Amm'r J. r 

